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Re: RE: Pre-engineered Metal Building

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I've never drilled through the rigid frame colum to connect my hairpin.  I've also never considered mechanical connection to the anchor bolts.

In this part of the world Pre-Eng buildings are typically used for wareshouses and so the rigid frame can start 4' above grade.  This protects the metal cladding from grader blades and snow build up.  I've actually seen some pre-eng buildings with 20' high snow piles right up agains the building.  Run some numbers on that.

I use hairpins frequently if the lateral forces are low.  I transfer the load through the pilaster and design the pilaster with vert. and hor. reinforcing steel to handle the moment.

The angle for the hairpins has more to do (in my mind) with finding enough area of steel reinforcing in the slab to equal the amount of force I need to transfer.  I extend the length of the hairpin until the horizontal force from the hairpin can be transferred into the area of steel in the slab.

I've changed my slab on grade designs for higher areas of steel of slab reinforcment to shorten my lengths of hairpin.   When you make the hairpin angle remember to take the correct vector component of force to transfer into the slab.

So essentially, I don't consider poly under slab or high and low frictions or passive pressures.  I use the mesh of steel inside the slab on grade to act as my tension tendons.

For larger spans like rec centres or hockey arenas  Tendons become more viable because the hor. force is so big on the clear span.

John Riley - you mentioned using deformed bars for tendons.  Please advise why.

Hope this helps.